刺参耳状幼体体长遗传力的估计

Heritability of auricularia larval body length for sea cucumber Apostichopus japonicus Selenka

基于全同胞组内相关法估计刺参（Apostichopus japonicus Selenka）耳状幼体初中期体长的遗传力.实验中的30个亲参来自人工养殖的成体刺参群体,亲本交配采用巢式不平衡设计,通过人工授精技术,构建了8个半同胞家系和22个全同胞家系.在耳状幼体初期和中期,每个全同胞家系分别测定40～70个后代个体体长.利用SAS软件的GLM过程,计算表型变量的原因方差组分,估算体长遗传力.分析结果显示,雌性遗传方差组分均显著大于雄性遗传方差组分（P＜0.05）,雌性遗传方差组分存在显著的母性效应（P＜0.05）.基于父系半同胞组内相关法计算的狭义遗传力是刺参耳状幼体初中期体长狭义遗传力的无偏估计值,估计值分别为0.74和0.75.结果表明,基于刺参耳状幼体体长的加性遗传方差较大,选择育种对于刺参幼体早期生长的改良具有较大的潜力.[中国水产科学,2006,13（3）：378-383]

Sea cucumbers belong to the phylum Echinodermata, class Holothuroidea. The temperate species, Apostichopus japonicus Selenka, naturally distributed in Bohai Bay and the Yellow Sea, is the most valuable due to its nutritional and supposed medicinal properties. With the rapid expansion and intensification of sea cucumber farming, various questions such as diseases, bad quality of larvas and less natural resources, have occurred and been serious, causing economic losses. They have become the limiting factors in the sustaining development of this industry. At last, these questions are resolved by provided excellent breeds provided by using the selecting breeding program. Before selection program can be started, breeding objectives must be defined exactly. In most species, growth traits were as the important economic traits. In the breeding program, heritability is the most basic parameter for the estimate of breeding value and selecting index, the establishment of breeding plan. In this paper, body length heritability of sea cucumber auricularia larval was estimated by means of intra group correlation of full-sib. A total of 30 maturing sea cucumber were from the population cultured. Eight sires and twenty two dams were mated by an unbalanced nest design. Each sire was mated to two or three dams, producing 8 half-sib groups and 22 full-sib families. Each full-sib family was reared separately and all families were given as equal environmental conditions as possible. The sea cucumber larvas were assessed for body length at initial stage and middle stage of auricularia （40- 70 inds. for each family）. Causal components of phenotypic variance were calculated with the GLM procedure of the SAS software. Analysis of variance demonstrated great differences in body length of larvas from different females mated with the same male and between males. This result also showed that the significant maternal effect was present because paternal genetic variance was significantly more than maternal genetic variance. Heritabilities in narrow sense of paternal half-sib and maternal half-sib and full sib of body length of initial and middle stage auricularia were 0.735 6, 0.870 0, 0.802 8 and 0.751 1, 0.915 0, 0.833 1, respectively. Hence, it was concluded that the heritability estimates （0.74,0.75） obtained from intra group correlation of paternal half-sib were precise and unbiased for body length of auricularia at initial stage and middle stage. Estimates of heritabilities in the narrow sense generally ranged from 0.2 -0.7 in most marine fish and shellfish species. In our study, the estimates of heritabilities in the narrow sense for body length at initial and middle stage ranged from 0.74 - 0.75, larger than those reported for other marine species. It is well known larger heritability could be estimated by the full-sib intra-group correlation analysis because it included maternal effect and dominant effect. The development stage of sea cucumber was also one important factor for the exact estimate of heritability. The larger heritability would be estimated at the juvenile stage because larval growth was affected by the maternal effect. With the development of the sea cucumber, m3aller heritability would be estimated due to less maternal effect. The estimated heritability indicated significant additive variation for body length at the initial and middle stage of auricularia. It was suggested that the effect for improvement through selection was particularly good for body length at auricularia larva stage of sea cucumber.